1. Field of the Invention
The present invention relates to a process for preparing a lactulose-containing powder for feed. More particularly, the present invention relates to a process for preparing a free-flowable lactulose-containing powder of high concentration for feed at a moderate price from cheese whey or casein whey which is a byproduct of dairy plants, or partially delactosed whey, or a permeate obtained by ultrafiltration of whey or skim milk to recover protein. More specifically, it relates to a process for preparing a free-flowing lactulose-containing powder for feed containing about 6.0 to 25% of lactulose at a low cost. This is accomplished by adding a specific amount of calcium hydroxide to a lactose-containing solution, heating the resulting mixed solution under specific conditions to cause the isomerization reaction of lactose and homogenizing, concentrating and drying the resulting lactulose-containing solution as it is.